title: The structure of a glycoside hydrolase family 81 endo-β-1,3-glucanase.
abstract: Endo-β-1,3-glucanases catalyze the hydrolysis of β-1,3-glycosidic linkages in glucans. They are also responsible for rather diverse physiological functions such as carbon utilization, cell-wall organization and pathogen defence. Glycoside hydrolase (GH) family 81 mainly consists of β-1,3-glucanases from fungi, higher plants and bacteria. A novel GH family 81 β-1,3-glucanase gene (RmLam81A) from Rhizomucor miehei was expressed in Escherichia coli. Purified RmLam81A was crystallized and the structure was determined in two crystal forms (form I-free and form II-Se) at 2.3 and 2.0 Å resolution, respectively. Here, the crystal structure of a member of GH family 81 is reported for the first time. The structure of RmLam81A is greatly different from all endo-β-1,3-glucanase structures available in the Protein Data Bank. The overall structure of the RmLam81A monomer consists of an N-terminal β-sandwich domain, a C-terminal (α/α)6 domain and an additional domain between them. Glu553 and Glu557 are proposed to serve as the proton donor and basic catalyst, respectively, in a single-displacement mechanism. In addition, Tyr386, Tyr482 and Ser554 possibly contribute to both the position or the ionization state of the basic catalyst Glu557. The first crystal structure of a GH family 81 member will be helpful in the study of the GH family 81 proteins and endo-β-1,3-glucanases.
authors.affiliation: Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhou
authors.forename: Zhongzhou
authors.initials: Z
authors.lastname: Chen
authors.forename: Qiaojuan
authors.initials: Q
authors.lastname: Yan
authors.forename: Shaoqing
authors.initials: S
authors.lastname: Yang
authors.forename: Rolf
authors.initials: R
authors.lastname: Hilgenfeld
authors.forename: Zhengqiang
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D004693:Glucan Endo-1,3-beta-D-Glucosidase / Q000737:chemistry* / Q000378:metabolism; D037102:Lectins / Q000737:chemistry* / Q000378:metabolism; D020103:Rhizomucor / Q000201:enzymology* / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D005656:Fungal Proteins; D037102:Lectins; C037937:glucan-binding proteins; D004693:Glucan Endo-1,3-beta-D-Glucosidase
keywords: Rhizomucor miehei; endo-β-1,3-glucanases; family 81; glycoside hydrolases; three-dimensional structure